hostnamed: expose local AF_VSOCK CID among other host info

This is a host identifier of major relevance, since it is how you
connect to this system if it is a VM, hence expose this nicely.

diff --git a/man/org.freedesktop.hostname1.xml b/man/org.freedesktop.hostname1.xml
index 577e64dcd7edd5565b37f7d40e5c2e36ca7242d5..61d9831ca6b8a5aaaccaa8a6c7b5fe4165aa3149 100644 (file)
--- a/man/org.freedesktop.hostname1.xml
+++ b/man/org.freedesktop.hostname1.xml
@@ -99,6 +99,8 @@ node /org/freedesktop/hostname1 {
       readonly ay MachineID = [...];
       @org.freedesktop.DBus.Property.EmitsChangedSignal("const")
       readonly ay BootID = [...];
+      @org.freedesktop.DBus.Property.EmitsChangedSignal("const")
+      readonly u VSockCID = ...;
   };
   interface org.freedesktop.DBus.Peer { ... };
   interface org.freedesktop.DBus.Introspectable { ... };
@@ -120,10 +122,6 @@ node /org/freedesktop/hostname1 {
 
     <!--property FirmwareDate is not documented!-->
 
-    <!--property MachineID is not documented!-->
-
-    <!--property BootID is not documented!-->
-
     <!--Autogenerated cross-references for systemd.directives, do not edit-->
 
     <variablelist class="dbus-interface" generated="True" extra-ref="org.freedesktop.hostname1"/>
@@ -196,6 +194,8 @@ node /org/freedesktop/hostname1 {
 
     <variablelist class="dbus-property" generated="True" extra-ref="BootID"/>
 
+    <variablelist class="dbus-property" generated="True" extra-ref="VSockCID"/>
+
     <!--End of Autogenerated section-->
 
     <para>Whenever the hostname or other metadata is changed via the daemon,
@@ -287,6 +287,18 @@ node /org/freedesktop/hostname1 {
     purpose of those properties is to allow remote clients to access this information over D-Bus. Local
     clients can access the information directly.</para>
 
+    <para><varname>MachineID</varname> expose the 128bit machine ID, see
+    <citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry> for
+    details.</para>
+
+    <para><varname>BootID</varname> expose the 128bit boot ID, as per
+    <filename>/proc/sys/kernel/random/boot_id</filename>.</para>
+
+    <para><varname>VSockCID</varname> exposes the system's local <constant>AF_VSOCK</constant> CID (Context
+    Identifier, i.e. address) for the system, if one is available in the virtual machine environment. Set to
+    <constant>UINT32_MAX</constant> otherwise. See <citerefentry project="man-pages"><refentrytitle>vsock</refentrytitle><manvolnum>7</manvolnum></citerefentry> for
+    details.</para>
+
     <refsect2>
       <title>Methods</title>
 
@@ -440,8 +452,8 @@ node /org/freedesktop/hostname1 {
       <para><varname>OperatingSystemSupportEnd</varname>,
       <varname>FirmwareVendor</varname>, and
       <varname>FirmwareDate</varname> were added in version 253.</para>
-      <para><varname>MachineID</varname>, and
-      <varname>BootID</varname> were added in version 256.</para>
+      <para><varname>MachineID</varname>, <varname>BootID</varname> and
+      <varname>VSockCID</varname> were added in version 256.</para>
     </refsect2>
   </refsect1>
 </refentry>

diff --git a/src/hostname/hostnamectl.c b/src/hostname/hostnamectl.c
index 14fc16090959549552469a90a59a0349e818bed0..4b92ac2b230349adc343923ca5923b23108bdebf 100644 (file)
--- a/src/hostname/hostnamectl.c
+++ b/src/hostname/hostnamectl.c
@@ -24,6 +24,7 @@
 #include "main-func.h"
 #include "parse-argument.h"
 #include "pretty-print.h"
+#include "socket-util.h"
 #include "spawn-polkit-agent.h"
 #include "terminal-util.h"
 #include "verbs.h"
@@ -58,6 +59,7 @@ typedef struct StatusInfo {
         usec_t firmware_date;
         sd_id128_t machine_id;
         sd_id128_t boot_id;
+        uint32_t vsock_cid;
 } StatusInfo;
 
 static const char* chassis_string_to_glyph(const char *chassis) {
@@ -191,6 +193,14 @@ static int print_status_info(StatusInfo *i) {
                         return table_log_add_error(r);
         }
 
+        if (i->vsock_cid != VMADDR_CID_ANY) {
+                r = table_add_many(table,
+                                   TABLE_FIELD, "AF_VSOCK CID",
+                                   TABLE_UINT32, i->vsock_cid);
+                if (r < 0)
+                        return table_log_add_error(r);
+        }
+
         if (!isempty(i->virtualization)) {
                 r = table_add_many(table,
                                    TABLE_FIELD, "Virtualization",
@@ -332,7 +342,9 @@ static int get_one_name(sd_bus *bus, const char* attr, char **ret) {
 }
 
 static int show_all_names(sd_bus *bus) {
-        StatusInfo info = {};
+        StatusInfo info = {
+                .vsock_cid = VMADDR_CID_ANY,
+        };
 
         static const struct bus_properties_map hostname_map[]  = {
                 { "Hostname",                  "s",  NULL,          offsetof(StatusInfo, hostname)         },
@@ -354,6 +366,7 @@ static int show_all_names(sd_bus *bus) {
                 { "FirmwareDate",              "t",  NULL,          offsetof(StatusInfo, firmware_date)    },
                 { "MachineID",                 "ay", bus_map_id128, offsetof(StatusInfo, machine_id)       },
                 { "BootID",                    "ay", bus_map_id128, offsetof(StatusInfo, boot_id)          },
+                { "VSockCID",                  "u",  NULL,          offsetof(StatusInfo, vsock_cid)        },
                 {}
         }, manager_map[] = {
                 { "Virtualization",            "s",  NULL,          offsetof(StatusInfo, virtualization)   },

diff --git a/src/hostname/hostnamed.c b/src/hostname/hostnamed.c
index f0e643822a3bc6c2e080eea9bd8c48ad15171385..d629a07d0fbab202dca167454c4406528abcbe5a 100644 (file)
--- a/src/hostname/hostnamed.c
+++ b/src/hostname/hostnamed.c
@@ -6,6 +6,8 @@
 #include <sys/types.h>
 #include <unistd.h>
 
+#include "sd-device.h"
+
 #include "alloc-util.h"
 #include "bus-common-errors.h"
 #include "bus-get-properties.h"
@@ -28,10 +30,10 @@
 #include "os-util.h"
 #include "parse-util.h"
 #include "path-util.h"
-#include "sd-device.h"
 #include "selinux-util.h"
 #include "service-util.h"
 #include "signal-util.h"
+#include "socket-util.h"
 #include "stat-util.h"
 #include "string-table.h"
 #include "strv.h"
@@ -1033,6 +1035,22 @@ static int property_get_boot_id(
         return bus_property_get_id128(bus, path, interface, property, reply, &id, error);
 }
 
+static int property_get_vsock_cid(
+                sd_bus *bus,
+                const char *path,
+                const char *interface,
+                const char *property,
+                sd_bus_message *reply,
+                void *userdata,
+                sd_bus_error *error) {
+
+        unsigned local_cid = VMADDR_CID_ANY;
+
+        (void) vsock_get_local_cid(&local_cid);
+
+        return sd_bus_message_append(reply, "u", (uint32_t) local_cid);
+}
+
 static int method_set_hostname(sd_bus_message *m, void *userdata, sd_bus_error *error) {
         Context *c = ASSERT_PTR(userdata);
         const char *name;
@@ -1333,6 +1351,7 @@ static int method_describe(sd_bus_message *m, void *userdata, sd_bus_error *erro
         _cleanup_(sd_bus_message_unrefp) sd_bus_message *reply = NULL;
         _cleanup_(json_variant_unrefp) JsonVariant *v = NULL;
         sd_id128_t machine_id, boot_id, product_uuid = SD_ID128_NULL;
+        unsigned local_cid = VMADDR_CID_ANY;
         Context *c = ASSERT_PTR(userdata);
         bool privileged;
         struct utsname u;
@@ -1404,6 +1423,8 @@ static int method_describe(sd_bus_message *m, void *userdata, sd_bus_error *erro
         if (r < 0)
                 return log_error_errno(r, "Failed to get boot ID: %m");
 
+        (void) vsock_get_local_cid(&local_cid);
+
         r = json_build(&v, JSON_BUILD_OBJECT(
                                        JSON_BUILD_PAIR("Hostname", JSON_BUILD_STRING(hn)),
                                        JSON_BUILD_PAIR("StaticHostname", JSON_BUILD_STRING(c->data[PROP_STATIC_HOSTNAME])),
@@ -1430,7 +1451,8 @@ static int method_describe(sd_bus_message *m, void *userdata, sd_bus_error *erro
                                        JSON_BUILD_PAIR_ID128("MachineID", machine_id),
                                        JSON_BUILD_PAIR_ID128("BootID", boot_id),
                                        JSON_BUILD_PAIR_CONDITION(!sd_id128_is_null(product_uuid), "ProductUUID", JSON_BUILD_ID128(product_uuid)),
-                                       JSON_BUILD_PAIR_CONDITION(sd_id128_is_null(product_uuid), "ProductUUID", JSON_BUILD_NULL)));
+                                       JSON_BUILD_PAIR_CONDITION(sd_id128_is_null(product_uuid), "ProductUUID", JSON_BUILD_NULL),
+                                       JSON_BUILD_PAIR_CONDITION(local_cid != VMADDR_CID_ANY, "VSockCID", JSON_BUILD_UNSIGNED(local_cid))));
 
         if (r < 0)
                 return log_error_errno(r, "Failed to build JSON data: %m");
@@ -1475,6 +1497,7 @@ static const sd_bus_vtable hostname_vtable[] = {
         SD_BUS_PROPERTY("FirmwareDate", "t", property_get_firmware_date, 0, SD_BUS_VTABLE_PROPERTY_CONST),
         SD_BUS_PROPERTY("MachineID", "ay", property_get_machine_id, 0, SD_BUS_VTABLE_PROPERTY_CONST),
         SD_BUS_PROPERTY("BootID", "ay", property_get_boot_id, 0, SD_BUS_VTABLE_PROPERTY_CONST),
+        SD_BUS_PROPERTY("VSockCID", "u", property_get_vsock_cid, 0, SD_BUS_VTABLE_PROPERTY_CONST),
 
         SD_BUS_METHOD_WITH_ARGS("SetHostname",
                                 SD_BUS_ARGS("s", hostname, "b", interactive),

diff --git a/units/systemd-hostnamed.service.in b/units/systemd-hostnamed.service.in
index 31b45e0fa8b11c81ae55605ae6eee5a1e2e994d9..1cc15dd7cfd21cd0515e2ee2394b2d7f2f61fdb0 100644 (file)
--- a/units/systemd-hostnamed.service.in
+++ b/units/systemd-hostnamed.service.in
@@ -22,7 +22,7 @@ IPAddressDeny=any
 LockPersonality=yes
 MemoryDenyWriteExecute=yes
 NoNewPrivileges=yes
-PrivateDevices=yes
+DeviceAllow=/dev/vsock r
 PrivateNetwork=yes
 PrivateTmp=yes
 ProtectProc=invisible